- ID:
- ivo://CDS.VizieR/J/AJ/77/797
- Title:
- NRAO 5GHz Strong Source Survey
- Short Name:
- J/AJ/77/797
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 140-ft telescope at the National Radio Astronomy Observatory has been used to extend the 5-GHz strong source (S) survey over an area of 1.14 steradian. Some 240 sources have been detected in this region, of which 135 are above the completeness limit of 0.6f.u. The distribution of spectral indices for sources above the completeness limit is much broader than for samples selected from long-wavelength surveys, owing to an increase in the fraction of compact sources with flat spectra. For about half of the sources selected at 6 cm, the spectral index {alpha}>-0.5. Analysis of the dependence of the spectral index on the flux density shows that, as expected from the 408-MHz number counts and spectral index distribution, at 5 GHz there are fewer flat spectra among the weak sources than among the stronger ones. The spectral index distributions for the identified galaxies and quasars show the familiar forms: the galaxies have a strong concentration near {alpha}=-0.8 with a small tail extending toward flat spectra. The quasars show a much broader distribution of indices, but the fraction (80%) of quasars having flat spectra ({alpha}>-0.5) is much greater than that found in the low-frequency surveys. The number-flux density relation for various groups of sources selected from the 5-GHz survey show that the anomalously steep slope is confined to (a) unidentified sources, (b) sources with steep spectra ({alpha}<-0.5), and (c) sources located in the north galactic hemisphere. Sources identified with radio galaxies or quasars, or which have flat spectra, or which are in the south galactic hemisphere all show a number-flux density slope near -1.5.
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Search Results
- ID:
- ivo://CDS.VizieR/J/other/A+C/25.176
- Title:
- NVSS and FIRST variable sources
- Short Name:
- J/other/A+C/25.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the present study we have cross-correlated NVSS and FIRST radio catalogues having radio flux measurements at the same 1.4GHz frequency. This way we benefit from repeated observations from both catalogues, as they give more accurate positions and fluxes and more important, reveal large differences between the two measured fluxes, thus allowing to establish radio variability. As a result 79382 radio variables have been revealed, including 6301 with flux differences at 1.4GHz larger than 15mJy, 1917 with flux differences 45mJy and 260 with flux differences 200mJy. By using a special technique (Mickaelian & Sinamyan 2010 (J/MNRAS/407/681) Mickaelian+ 2011 (J/MNRAS/415/1061)), 2425 optically variable objects out of 6301 radio sources have been revealed. 2425 radio sources with both high radio and optical variability into four categories have been divided. 1206 (19%) out of 6301 radio sources have activity types from available catalogues and 619 (25.5%) out of 2425 radio sources with at the same time radio and optical variability have activity types from available catalogues. In addition, 279 radio sources out of 2425 have high variability in optical range. We have established their activity types when available. The IR fluxes and colours for the 6301 variable radio sources have been studied. Colour-colour diagrams show that most of the "unknown" sources are galaxies. The activity types for 110 (42%) out of 260 extremely high variable radio sources also have been retrieved.
- ID:
- ivo://CDS.VizieR/J/AZh/71/352
- Title:
- Objects of 1988 Zenith Sky Survey
- Short Name:
- J/AZh/71/352
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of optical identification of radio sources Zenith Sky Survey with the Palomar Sky Survey prints are presented. The sky survey was conducted with a RATAN-600 radio telescope at 8.0cm in a ring-aperture operation mode. All the objects belong to the radio source population with flux densities in a range from 5 to 50mJy. The mean value of the spectral index distribution for the sources identified with other catalogs was found to be equal to -0.9 at 8.0cm.
- ID:
- ivo://CDS.VizieR/J/ApJ/810/85
- Title:
- Observation of first Fermi-LAT sources at Parkes
- Short Name:
- J/ApJ/810/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a search with the Parkes radio telescope of 56 unidentified Fermi-Large Area Telescope (LAT) gamma-ray sources, we have detected 11 millisecond pulsars (MSPs), 10 of them discoveries, of which five were reported by Kerr et al (2012ApJ...748L...2K). We did not detect radio pulsations from six other pulsars now known in these sources. We describe the completed survey, which included multiple observations of many targets conducted to minimize the impact of interstellar scintillation, acceleration effects in binary systems, and eclipses. We consider that 23 of the 39 remaining sources may still be viable pulsar candidates. We present timing solutions and polarimetry for five of the MSPs and gamma-ray pulsations for PSR J1903-7051 (pulsations for five others were reported in the second Fermi-LAT catalog of gamma-ray pulsars). Two of the new MSPs are isolated and five are in >1 day circular orbits with 0.2-0.3 M_{sun}_ presumed white dwarf companions. PSR J0955-6150, in a 24 day orbit with a 0.2-0.3 M_{sun}_ companion but eccentricity of 0.11, belongs to a recently identified class of eccentric MSPs. PSR J1036-8317 is in an 8 hr binary with a>0.14 M_{sun}_ companion that is probably a white dwarf. PSR J1946-5403 is in a 3 hr orbit with a>0.02 M_{sun}_ companion with no evidence of radio eclipses.
- ID:
- ivo://CDS.VizieR/J/ApJS/194/29
- Title:
- Observations of blazars at 15GHz
- Short Name:
- J/ApJS/194/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope provides an unprecedented opportunity to study gamma-ray blazars. To capitalize on this opportunity, beginning in late 2007, about a year before the start of LAT science operations, we began a large-scale, fast-cadence 15GHz radio monitoring program with the 40m telescope at the Owens Valley Radio Observatory (OVRO). This program began with the 1158 northern ({delta}>-20{deg}) sources from the Candidate Gamma-ray Blazar Survey and now encompasses over 1500 sources, each observed twice per week with about 4mJy (minimum) and 3% (typical) uncertainty. Here, we describe this monitoring program and our methods, and present radio light curves from the first two years (2008 and 2009). As a first application, we combine these data with a novel measure of light curve variability amplitude, the intrinsic modulation index, through a likelihood analysis to examine the variability properties of subpopulations of our sample.
- ID:
- ivo://CDS.VizieR/J/A+A/489/49
- Title:
- Observations of candidate GPS sources
- Short Name:
- J/A+A/489/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gigahertz-Peaked Spectrum (GPS) sources are likely the precursors of local radio galaxies. Existing GPS source samples are small (<200). We aim to extend the available sample of the Gigahertz-Peaked Spectrum (GPS) and High Frequency Peaker (HFP) sources in order to study their nature with greater detail and higher statistical significance.
- ID:
- ivo://CDS.VizieR/J/ApJ/669/446
- Title:
- Observations of SiO masers
- Short Name:
- J/ApJ/669/446
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of SiO millimeter line observations of a sample of known SiO maser sources covering a wide dust temperature range. A cold part of the sample was selected from the SiO maser sources found in our recent SiO maser survey of cold dusty objects. The aim of the present research is to investigate the causes of the correlation between infrared colors and SiO maser intensity ratios among different transition lines. In particular, the correlation between infrared colors and SiO maser intensity ratio among the J=1-0 v=1, 2, and 3 lines are our main concern in this paper. We observed in total 75 SiO maser sources with the Nobeyama 45m telescope quasi-simultaneously in the SiO J=1-0 v=0, 1, 2, 3, 4 and J=2-1 v=1, 2 lines. We also observed the sample in the ^29^SiO J=1-0 v=0 and J=2-1 v=0 lines, ^30^SiO J=1-0 v=0 line, and the H_2_O 61,6-52,3 line.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A82
- Title:
- Observed chemical structure of L1544
- Short Name:
- J/A+A/606/A82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the emission maps of 39 different molecular transitions belonging to 22 different molecules in the central 6.25 arcmin^2^ of L1544. We classified our sample in five families, depending on the location of their emission peaks within the core. Furthermore, to systematically study the correlations among different molecules, we have performed the principal component analysis (PCA) on the integrated emission maps. The PCA allows us to reduce the amount of variables in our dataset. Finally, we compare the maps of the first three principal components with the H_2_ column density map, and the T_dust_ map of the core. The results of our qualitative analysis is the classification of the molecules in our dataset in the following groups: (i) the c-C_3_H_2_ family (carbon chain molecules like C_3_H and CCS), (ii) the dust peak family (nitrogen-bearing species like N_2_H^+^ ), (iii) the methanol peak family (oxygen-bearing molecules like methanol, SO and SO_2_, (iv) the HNCO peak family (HNCO, propyne and its deuterated isotopologues). Only HC^18^O^+^ and ^13^CS do not belong to any of the above mentioned groups. The principal component maps allow us to confirm the (anti-)correlations among different families that were described in a first qualitative analysis, but also points out the correlation that could not be inferred before. For example, the molecules belonging to the dust peak and the HNCO peak families correlate in the third principal component map, hinting on a chemical/physical correlation.
- ID:
- ivo://CDS.VizieR/J/AJ/98/419
- Title:
- Observed quantities from B3 sources
- Short Name:
- J/AJ/98/419
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains results of a large program of optical identifications of radio sources from the Third Bologna (B3) Catalog (Ficarra et al., 1985A&AS...59..255F, Cat.<VIII/37>). A homogeneous sample of 1103 radio sources, selected from the B3 catalog at 408 MHz and covering a flux density range from 2.0 to 0.1 Jy, has been mapped at 1465 MHz using the VLA at 15" resolution. Both positional and structural information have been derived and are presented here. Optical identifications have been attempted for all of the sources within the range of right ascension studied, using the Palomar Sky Survey prints, resulting in 354 proposed identifications. The RA range was restricted to exclude sky areas at low galactic latitude, because obscuration makes these unsuitable for optical identifications, and confusion makes them unsuitable for VLA snapshot-mode observations. Thus the samples were selected only from the RA intervals 23h-3h, 7h-15h. The number of rows of this table (1474) is larger than the number of sources (1103) because each radio component of multiple sources is listed as a separate line.
- ID:
- ivo://CDS.VizieR/J/ApJ/880/138
- Title:
- Observed transitions of CH_3_OH and CH_3_CHO
- Short Name:
- J/ApJ/880/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IRAM 30m Observations toward eight protostellar outflow sources were taken in the 96-176GHz range. Transitions of CH_3_OH and CH_3_CHO were detected in seven of them. The integrated emissions of the transitions of each species that fell into the observed frequency range were measured and fit using RADEX and LTE models. Column densities and gas properties inferred from this fitting are presented. The ratio of the A and E-type isomers of CH_3_OH indicates that the methanol observed in these outflows was formed on the grain surface. Both species demonstrate a reduction of terminal velocity in their line profiles in faster outflows, indicating destruction in the post-shock gas phase. This destruction, and a near constant ratio of the CH_3_OH and CH_3_CHO column densities, imply it is most likely that CH_3_CHO also forms on the grain surface.